The reaction is disclosed in Japanese Patent Application 51348/65. It is there stated that acryloylsilanes of the formula ##STR1## wherein R.sup.1 is hydrogen or methyl, R.sup.2 and R.sup.3 are identical or different alkyls of 1 to 4 carbon atoms, m is 0, 1 or 2, and n is a whole number from 1 to 4, can be prepared by reacting a solid alkali metal salt of methacrylic acid or acrylic acid with a chloroalkylsilane of the formula ##STR2## wherein R.sup.2, R.sup.3, m and n have the meanings previously defined, in the presence of a quaternary ammonium salt as a solid/liquid phase transfer catalyst.
The Japanese application mentions triethylamine, dimethylaniline, tetramethylammonium chloride and benzyltrimethylammonium chloride as suitable phase transfer catalysts. The two last-mentioned compounds are used as phase transfer catalysts in the Examples of the Japanese application for the reaction between the solid phase, consisting of the alkali metal salt of methacrylic or acrylic acid, and the liquid phase consisting of the chloroalkylsilane.
When these catalysts are used, high reaction temperatures of 140.degree. to 180.degree. C. are required, and the reaction time is in some cases up to 10 hours. Furthermore, a large excess of chloroalkylsilane, which may be up to 10 times the molar amount of alkali metal methacrylate or alkali metal acrylate is required. Moreover, solvents such as, for example, dimethyl-formamide, toluene or xylene must be used.
The yields of organosilane in this known process are substantially below 90% and frequently only 70%. With a molar ratio of alkali metal (meth)-acrylate/chloroalkylsilane of 1:1, the yield is actually only 65%, and large amounts of polymeric material are formed as a by-product. In addition, the large excess of chloroalkylsilane, the solvent, the long reaction time and the high reaction temperatures are decisive disadvantages. Long reaction times and a large excess of chlorosilane lead to a considerable reduction in the space-time yield. Moreover, the large excess of chloroalkylsilane and the use of a solvent have an adverse effect on the energy balance in the purification of the organosilane target product by distillation. The use of a solvent also has an adverse effect on the yield of organosilane.
High temperatures not only favor the formation of undesired polymeric by-products, but also lead to a virtually quantitative decomposition of the quaternary ammonium salt. Those skilled in the art are aware of the fact that quaternary salts decompose rapidly above 110.degree. to 120.degree. C. As a result of an anion exchange of halide for (meth)acrylate, silicon-free methacrylates or acrylates and tertiary amines are formed in the thermal decomposition of the quaternary ammonium salt. The decomposition products formed by trimethylbenzylammonium methacrylate or acrylate may be the corresponding high-boiling-point benzyl methacrylate or acrylate and dimethylbenzylamine, which can be separated from the acryloylsilane only with difficulty by distillation. Those skilled in the art know that these impurities may considerably interfere with, or even prevent, the use of the acryloylsilanes of the formula I above. Thus, the benzyl esters form oily films on aqueous solutions of the acryloylsilanes and prevent the use of such solutions as sizes for glass fibers. On the other hand, tertiary amines may adversely affect the use of the acryloylsilanes in peroxide-initiated polymerization reactions, since they may increase the polymerization rate in an undesirable manner.